Formaldehyde-free melamine carbohydrate binders for improved fire-resistant fibrous materials

ABSTRACT

Embodiments of the present technology include a formaldehyde-free binder composition. The composition may include melamine. The composition may also include a reducing sugar. In addition, the binder composition may include a non-carbohydrate aldehyde or ketone. Embodiments may also include a method of making a formaldehyde-free binder composition. The method may include dissolving melamine in an aqueous solution of a reducing sugar. The concentration of the reducing sugar may be 30 wt. % to 70 wt. % of the aqueous solution, which may be at a temperature of 50° C. to 100° C. The method may also include adding a non-carbohydrate aldehyde or ketone to the dissolved melamine in the aqueous solution to form a binder solution. The temperature of the aqueous solution of the dissolved melamine may be 50° C. to 100° C. during the addition of the non-carbohydrate aldehyde or ketone. The method may further include reducing the temperature of the binder solution.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of pending U.S. application Ser. No.15/237,949 filed Aug. 16, 2016, which is a divisional of U.S.application Ser. No. 14/323,199 filed Jul. 3, 2014, now U.S. Pat. No.9,447,221 issued Sep. 30, 2016.

BACKGROUND

Organic binders for composite fiber products such as fiberglassinsulation are moving away from traditional formaldehyde-basedcompositions. Formaldehyde is considered a probable human carcinogen, aswell as an irritant and allergen, and its use is increasingly restrictedin building products, textiles, upholstery, and other materials. Inresponse, binder compositions have been developed that reduce oreliminate formaldehyde from the binder composition.

One type of these formaldehyde-free binder compositions rely onesterification reactions between carboxylic acid groups in polycarboxypolymers and hydroxyl groups in alcohols. Water is the main byproduct ofthese covalently crosslinked esters, which makes these binders moreenvironmentally benign, as compared to traditional formaldehyde-basedbinders. However, these formaldehyde-free binder compositions also makeextensive use of non-renewable, petroleum-based ingredients. Thus, thereis a need for formaldehyde-free binder compositions that rely less onpetroleum-based ingredients.

As an abundant and renewable material, carbohydrates have greatpotential to be an alternative to petroleum-based binders. Carbohydratesare already used as a component of some types for binders, such asMaillard binders that contain reaction products of reducing sugarcarbohydrates and amine reactants. Although these products may haveacceptable thermal and mechanical properties for low density fiber glassproducts, their fire resistance is typically lower than formaldehydecontaining resins for pipe insulation and other high densityfiberglass-based products. Thus, there is a need to improve the fireresistance of carbohydrate-containing binder compositions. These andother issues are addressed in the present Application.

BRIEF SUMMARY

Formaldehyde-free binder compositions that may include water-solublemelamine are described. Such binder compositions may be non-hazardousand may not generate formaldehyde, and the melamine in the binder mayimprove the fire and flame resistance of the binder. These binders mayoften include renewable components, such as reducing sugars. Thesebinders may be used in fiber-reinforced composites. Methods of makingthese binder compositions and these fiber-reinforced composites are alsodescribed.

Embodiments of the present technology include a formaldehyde-free bindercomposition. The composition may include melamine. The composition mayalso include a reducing sugar. In addition, the binder composition mayinclude a non-carbohydrate aldehyde or ketone.

Embodiments may also include a method of making a formaldehyde-freebinder composition. The method may include dissolving melamine in anaqueous solution of a reducing sugar. The concentration of the reducingsugar may be 30 wt. % to 70 wt. % of the aqueous solution, which may beat a temperature of 50° C. to 100° C. The method may also include addinga non-carbohydrate aldehyde or ketone to the dissolved melamine in theaqueous solution to form a binder solution. The temperature of theaqueous solution of the dissolved melamine may be 50° C. to 100° C.during the addition of the non-carbohydrate aldehyde or ketone. Themethod may further include reducing the temperature of the bindersolution to about 23° C.

Embodiments may include a fiber-reinforced composite. Thefiber-reinforced composite may include a plurality of fibers and abinder made from a formaldehyde-free binder composition. The binder mayinclude melamine, and the binder may include a reducing sugar. Inaddition, the binder may include a non-carbohydrate aldehyde or ketone.The binder may further include a curing catalyst.

Embodiments may further include a method of making a fiber-reinforcedcomposite. The method may include providing a plurality of fibers. Anoperation in the method may include contacting the plurality of fiberswith a formaldehyde-free binder composition to make a fiber-binderamalgam. The formaldehyde-free binder composition may include melamine,and the binder composition may also include a reducing sugar.Furthermore, the binder composition may include a non-carbohydratealdehyde or ketone. Additionally, the binder composition may include acuring catalyst. The method may also include heating the fiber-binderamalgam to a temperature of 100° C. to 250° C. to form thefiber-reinforced composite.

Additional embodiments and features are set forth in part in thedescription that follows, and in part will become apparent to thoseskilled in the art upon examination of the specification or may belearned by the practice of the invention. The features and advantages ofthe invention may be realized and attained by means of theinstrumentalities, combinations, and methods described in thespecification.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the remaining portions of thespecification and the drawings wherein like reference numerals are usedthroughout the several drawings to refer to similar components. In someinstances, a sublabel is associated with a reference numeral and followsa hyphen to denote one of multiple similar components. When reference ismade to a reference numeral without specification to an existingsublabel, it is intended to refer to all such multiple similarcomponents.

FIG. 1 shows a method of making a binder composition according toembodiments of the present technology;

FIG. 2 shows a method of making a fiber-reinforced composite accordingto embodiments of the present technology;

FIG. 3 depicts a simplified schematic of an exemplary fabrication systemfor making the fiber-containing composites according to embodiments ofthe present technology;

FIG. 4 shows a graph of mass retention at 500° C. versus time fordifferent binders according to embodiments of the present technology;

FIG. 5 shows a graph of tensile strength results for different moleratios of dextrose according to embodiments of the present technology;and

FIG. 6 shows the effect of different catalysts on the performance ofdogbone composites according to embodiments of the present technology.

DETAILED DESCRIPTION

Melamine and its salts, which include phosphate, sulfate, and borate,are known fire retardants. These salts, however, are generally notsoluble in water and thus may not be used in an aqueous solution toimprove the fire resistance of formaldehyde-free resins. Moreover, whilemelamine resins may be used with formaldehyde-free resins to improvefire resistance, these melamine resins may either contain formaldehydeor have low or limited solubility in water. Additionally, someformaldehyde-free melamine resins may not include renewable rawmaterials. Melamine binders may also not have been used to bind mineralor glass fibers.

Melamine as described herein may be water soluble and part of aformaldehyde-free binder composition for binding mineral or glassfibers. Although melamine typically has limited solubility in water,melamine was found to dissolve in a 30% to 70% solution of sugars (e.g.,dextrose) at a temperature of 50° C. to 100° C. Still, when thetemperature of the solution was cooled to room temperature, the solutionwas observed to precipitate melamine and to result in hard-settling ofmelamine. Adding a small amount of glyoxal to the hot solution ofmelamine and sugars was observed to prevent the precipitation ofmelamine when the solution was cooled to room temperature. Withoutintending to be bound by any particular theory, it is believed thatmelamine may have reacted with glyoxal and the resulting adduct may havebeen soluble in the sugar solution. The solubility of melamine in watermay be accomplished without the aid of a charged moiety or aquaternization agent.

The binder compositions may include a melamine compound, which may be asubstituted or unsubstituted melamine having the formula:

where R₁, R₂, R₃, R₄, R₅, and R₆ are independently chosen from ahydrogen moiety (H), an alkyl group, an aromatic group, an alcoholgroup, an aldehyde group, a ketone group, a carboxylic acid group, andan alkoxy group. Exemplary alkyl groups include straight-chained,branched, or cyclic hydrocarbons of varying size (e.g., C₁-C₁₂, C₁-C₈,C₁-C₄, etc.). Exemplary aromatic (i.e., aryl) groups include substitutedor unsubstituted phenyl moieties, among other aromatic constituents.Exemplary alcohol groups include —ROH, where R may be a substituted orunsubstituted, saturated or unsaturated, branched or unbranched, cyclicor acyclic, organic moiety. For example, R may be —(CH₂)_(n)—, where nmay be 1 to 12. Exemplary alcohols may also include polyols having twoor more hydroxyl groups (—OH) in alcohol group. Exemplary aldehydegroups include —RC(═O)H, where R may be a monovalent functional group(e.g., a single bond), or a substituted or unsubstituted, saturated orunsaturated, branched or unbranched, cyclic or acyclic, organic moiety,such as —(CH₂)_(n)—, where n may be 1 to 12. Exemplary ketone groups mayinclude —RC(═O)R′ where R and R′ can be variety of carbon containingconstituents. Exemplary carboxylic acid groups may include —R—COOH,where R may be a monovalent functional group, such as a single bond, ora variety of carbon-containing constituents. Exemplary alkoxy groupsinclude —OR_(x), where R_(x) is an alkyl group.

Embodiments of the present technology include a formaldehyde-free bindercomposition. The composition may include a melamine compound, such assubstituted or unsubstituted melamine. The composition may also includea reducing sugar. The mole or molar ratio of the melamine compound tothe reducing sugar may be from 1:3 to 1:12, 1:5 to 1:10, or 1:7 to 1:9in embodiments.

The reducing sugar may be any sugar having an aldehyde group, or aketone group that is capable of isomerizing to produce an aldehydegroup. Exemplary reducing sugars include monosaccharaides such asglucoses (e.g., dextrose), fructose, glyceraldehyde, and galactose. Theyalso include polysaccharaides such as lactose, maltose, xylose, andamylose, among others. The reducing sugar may include high fructose cornsyrup. The binder compositions may include a single reducing sugar or acombination of two or more reducing sugars as the reducing sugars in thecomposition.

In addition, the binder composition may include a compound with analdehyde or ketone. This aldehyde- or ketone-containing compound may bea compound that is not the reducing sugar. The compound may be anon-carbohydrate. Examples of non-carbohydrate ketones may includeacetone, methyl ethyl ketone, and pentanedione.

The aldehyde-containing compound may contain one or more aldehydefunctional groups. Exemplary aldehyde-containing compounds includeacetaldehyde, propanaldehyde, butyraldehyde, acrolein, furfural,glyoxal, gluteraldehyde, alkoxylated acetaldehyde, glutaric dialdehyde,and polyfurfural among others. Exemplary aldehyde-containing compoundsmay also include substituted glyoxal compounds having the formula:

where R₇ and R₈ may be independently hydrogen (H), an alkyl group, anaromatic group, an alcohol group, an aldehyde group, a ketone group, acarboxylic acid group, and an alkoxy group, among other groups.Aldehydes may be more effective than ketones in increasing thesolubility of the melamine resin in reducing sugars. The only aldehydesor ketones present in the composition may be limited to those in thereducing sugar, the aldehyde- or ketone-containing compound, and thesubstituted melamine.

The ratio of melamine to the aldehyde-containing compound may be 2:1 ora mole ratio with a greater amount of aldehyde-containing compound. Forexample, the ratio of the melamine compound to glyoxal may be from 2:1to 1:10, 2:1 to 1:5, 2:1 to 1:3, or 2:1 to 1:2. The mole ratio of themelamine compound:non-carbonhydrate aldehyde or ketone:reducing sugarmay be from 1:0.5:6 to 1:0.5:12. For example, the mole ratio ofmelamine:non-carbonhydrate aldehyde or ketone:reducing sugar may be from1:0.5:8 to 1:0.5:10.

The binder composition may further include a curing catalyst. Exemplarycatalysts may include alkaline catalysts and acidic catalysts. Theacidic catalysts may include Lewis acids (including latent acids andmetallic salts), as well as protic acids, among other types of acidcatalysts, including Brønsted acid catalysts. Lewis acid catalysts maybe a salt of a deprotonized anion such as a sulfate, sulfite, nitrate,nitrite, phosphate, halide, or oxyhalide anion in combination with oneor more metallic cations such as aluminum, zinc, iron, copper,magnesium, tin, zirconium, and titanium. Exemplary Lewis acid catalystsinclude aluminum sulfate, ferric sulfate, aluminum chloride, ferricchloride, aluminum phosphate, ferric phosphate, and sodium hypophosphite(SHP), among others. Exemplary latent acids include acid salts such asammonium sulfate, ammonium hydrogen sulfate, mono and dibasic ammoniumphosphate, ammonium chloride, and ammonium nitrate, among other latentacid catalysts. The curing catalyst may be a sulfate salt, a phosphatesalt, a borate salt, or combinations thereof. The sulfate salt, thephosphate salt, or the borate salt may include an ammonium salt.Exemplary metallic salts may include organo-titanates andorgano-zirconates (such as those commercially manufactured under thetradename Tyzor® by DuPont), organo-tin, and organo-aluminum salts,among other types of metallic salts. Exemplary protic acids includesulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, sulfonicacid compounds (i.e., R—S(═O)₂—OH) such as p-toluenesulfonic acid andmethanesulfonic acid, and carboxylic acids, among other protic acids.Catalyst compositions may also include combinations of two or morecatalysts, for example the combination of ammonium sulfate anddiammonium phosphate.

Exemplary concentrations of the catalyst (or combination of catalysts)in the binder composition may have a range from about 1 wt. % to about20 wt. % of the composition. For example, the catalyst concentration mayrange from about 1%, 2%, 3%, 4%, 5%, 6%, 7%, etc., on the low end, and10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20 wt. % on thehigh end. Exemplary catalyst concentrations may include about 5 wt. %,about 7.5 wt. %, about 8 wt. %, about 9 wt. %, and about 10 wt. %, amongother concentrations.

The binder may further include a melamine salt formed by the reaction ofthe melamine with the curing catalyst in the binder composition. Thecuring catalyst may act as a reaction catalyst even though it hasreacted with melamine. The melamine salt may improve the fire resistanceof the binder. A reaction with either the melamine or glyoxal asreactants may not result in a compound with an acidic moiety.

The pH of the present binder compositions may vary depending upon thetypes and relative concentrations of the components used. Typically thepH of the present binder compositions are slightly acidic to alkalinewith a pH range of about 6 to 8 (e.g., 6.5 to 7.5). The bindercompositions may have a pH that creates relatively little or noacid-based corrosion of metal fabrication equipment.

The binder composition may further include one or more additionalcomponents such as adhesion prompters, oxygen scavengers, solvents,emulsifiers, pigments, organic and/or inorganic fillers, anti-migrationaids, coalescent aids, wetting agents, biocides, plasticizers,organosilanes, anti-foaming agents, colorants, waxes, suspending agents,anti-oxidants, and secondary crosslinkers, among other components.Compounds such as urea, Dicy, and guanidine may be included in thebinder composition to further improve its fire resistance. Soluble orinsoluble (dispersion) fire retardants may be added. Such fireretardants may include melamine salts, phosphates, borates, halogenatedcompounds, and hydrated compounds. In some instances, some or all of theadditional components are pre-mixed with the binder composition beforeit is applied to fibers and cured. In additional instances, some or allof the additional components may be introduced to the curable, curing,and/or cured fiber-containing composite during or after the initialbinder composition is applied to the fibers. In these or otherinstances, the binder composition may be free of cellulose.

Embodiments may also include a method of making a formaldehyde-freebinder composition. FIG. 1 shows one such method 100 of making aformaldehyde-free binder composition. Method 100 may include dissolvinga melamine compound, such as unsubstituted melamine, in an aqueoussolution of a reducing sugar 102. The concentration of the reducingsugar may be 30 wt. % to 70 wt. % of the aqueous solution. For example,the concentration of the reducing sugar may be 40 wt. % to 60 wt. % or45 wt. % to 55 wt. %. The aqueous solution may be at a temperature of50° C. to 100° C. The reducing sugar may be any of the reducing sugarsdisclosed herein. Melamine may be dissolved in any of the mole ratios ofmelamine to the reducing sugar described herein.

Method 100 may also include adding a non-carbohydrate aldehyde or ketoneto the dissolved melamine in the aqueous solution to form a bindersolution 104. The temperature of the aqueous solution of the dissolvedmelamine may be 50° C. to 100° C. during the addition of thenon-carbohydrate aldehyde or ketone. The non-carbohydrate aldehyde orketone may be any of the non-carbohydrate aldehydes or ketones describedherein. The mole ratio of melamine to the non-carbohydrate aldehyde orketone may be any ratio disclosed herein.

The reaction product of melamine and the aldehyde- or ketone-containingcompound may act as a crosslinking agent for the reducing sugar. Duringa curing stage the crosslinking agent can bond to two or more reducingsugars (either polymerized or unpolymerized) to form a crosslinked,polymeric cured binder.

After adding all of the non-carbohydrate aldehyde or ketone, the methodmay further include maintaining a temperature of the binder solution at80° C. to 100° C. for about 60 minutes to 120 minutes. The method mayfurther include adding a curing catalyst to the binder solution. Thecuring catalyst may be any of the compounds previously described. Theaddition of the curing catalyst may include adding a 10 wt. % aqueoussolution of ammonium sulfate, diammonium phosphate, or a combination ofammonium sulfate and diammonium phosphate in a 1:1 ratio.

Method 100 may further include reducing the temperature of the bindersolution 106 to about 23° C. At this temperature, the binder solutionproduced by method 100 may not precipitate melamine.

Embodiments may include a fiber-reinforced composite. Thefiber-reinforced composite may include a plurality of fibers and abinder made from a formaldehyde-free binder composition. The bindercomposition may be any binder composition disclosed herein. Thefiber-containing composites may include woven or non-woven fibers boundtogether by a cured matrix of the binder. The plurality of fibers in thecomposite may include one or more types of fibers chosen from glassfibers, carbon fibers, mineral fibers, and organic polymer fibers, amongother kinds for fibers. At the conclusion of the curing stage, the curedbinder may be present as a secure coating on the fiber mat at aconcentration of approximately 0.5 to 50 percent by weight of thecomposition, for example the cured binder may be present at aconcentration of approximately 1 to 10 percent by weight of thecomposition.

The fiber-containing composites may take a variety of forms, for exampleconstruction materials including piping insulation, duct boards (e.g.,air duct boards), and building insulation, reinforcement scrim, androofing membranes, among other construction materials. Additionalexamples may include loose-fill blown insulation, duct liner, duct wrap,flexible duct media, pipe insulation, tank insulation, rigid plenumliner, textile duct liner insulation, equipment liner, oven insulation,elevated temperature board, elevated temperature wrap, elevatedtemperature panel, insulation batts and rolls, heavy density battinsulation, light density batt insulation, exterior foundationinsulation board, and marine hull insulation, among other materials. Thecomposites can also find use in printed circuit boards, batteryseparators, and filter stock, among other applications.

As shown in FIG. 2, embodiments may further include a method 200 ofmaking a fiber-reinforced composite. Method 200 may include providing aplurality of fibers 202. The plurality of fibers may include glassfibers or any of the fibers described herein. An operation in method 200may include contacting the plurality of fibers with a formaldehyde-freebinder composition to make a fiber-binder amalgam 204. Theformaldehyde-free binder composition may be any binder compositiondescribed herein.

The step of contacting the binder composition to the fibers may be doneby a variety of techniques including spraying, spin-curtain coating,curtain coating, and dipping-roll coating. The composition can beapplied to freshly-formed fibers, or to fibers that have been cooled andprocessed (e.g., cut, coated, sized, etc.). The binder may be providedto the applicator as a premixed composition or may be supplied to theapplicator in separate solutions for the crosslinking agent and thereducing sugar component. In some instances where the binder compositionincludes a solvent, a portion or all of the solvent may be removed fromthe composition before or after its application on the fibers.

Method 200 may also include heating the fiber-binder amalgam to atemperature of 100° C. to 250° C. to form the fiber-reinforced composite206. For example, the fiber-binder amalgam may be heated to atemperature of 150° C. to 200° C. to form the fiber-reinforcedcomposite. The amalgam may be heated to the curing temperature for aperiod of 1 minute to 100 minutes (e.g., 20 minutes to 80 minutes, 40minutes to 60 minutes, and 20 minutes).

The curing step may produce the finished fiber-containing composite,such as fiberglass insulation. In some exemplary methods, additionalagents like an anti-dusting agent may be applied during or following thecuring step.

FIG. 3 shows a simplified schematic of an exemplary fabrication system300 for making the fiber-containing composites described above. Thesystem 300 includes fiber supply unit 302 that supplies the fibers forthe composite. The fiber supply unit 302 may be filled with pre-madefibers, or may include equipment for making the fibers from startingmaterials such as molten glass or organic polymers. The fiber supplyunit 302 deposits the fibers 304 onto a porous conveyor belt 306 thattransports the fibers under the binder supply unit 308.

The binder supply unit 308 contains a liquid uncured binder composition310, that is deposited onto the fibers 304. In the embodiment shown, thebinder composition 310 is spray coated onto the fibers 304 with spraynozzles 312, however, other application techniques (e.g., curtaincoating, dip coating, etc.) may be used in addition to (or in lieu of)the spray coating technique illustrated by nozzles 312.

The binder composition 310 applied on fibers 304 forms a fiber andbinder amalgam on the top surface of the conveyor belt 306. The belt 306may be perforated and/or porous to allow excess binder composition 310to pass through the belt 306 to a collection unit (not shown) below. Thecollection unit may include filters and circulation pumps to recycle atleast a portion of the excess binder back to the binder supply unit 308.

The conveyor belt 306 transports the amalgam to an oven 314 where it isheated to a curing temperature and the binder composition starts tocure. The temperature of the oven 314 and the speed of the conveyor belt306 can be adjusted to control the curing time and temperature of theamalgam. In some instances, process conditions may be set to completelycure the amalgam into the fiber-containing composite. In additionalinstances, process conditions may be set to partially cure the amalgaminto a B-staged composite.

The amalgam may also be compressed prior to or during the curing stage.System 300 shows an amalgam being compressed by passing under a plate316 that tapers downward to decrease the vertical space available to thecuring amalgam. The amalgam emerges from under the plate 316 in acompressed state and has less thickness than when it first made contactwith the plate. The taper angle formed between the plate 316 andconveyor belt 306 can be adjusted to adjust the level of compressionplaced on the amalgam. The partially or fully cured composite thatemerges from under plate 316 can be used for a variety of applications,including construction materials such as pipe, duct, and/or wallinsulation, among other applications.

EXAMPLE 1

Melamine powder was added to and dispersed in a 50% solution of dextrosein water at ambient temperature in a three neck reactor equipped with astirrer and condenser. The mole ratio of unsubstituted melamine todextrose was varied from 1:3 to 1:12. The temperature was raised untilthe melamine dissolved completely, and a clear solution was obtained.The dissolution temperature of melamine was observed at a temperature of100° C. for the 1:3 melamine:dextrose solution and 65° C. for the 1:12melamine:dextrose solution.

Heating of the solution was stopped. A 40% solution of glyoxal in waterwas added to the hot melamine/dextrose solution. The mole ratio of ofmelamine to glyoxal varied from 1:0.5 to 1:3. After the addition ofglyoxal, an exotherm was observed. This exotherm may indicate that themelamine reacts with the glyoxal.

The solution was a pale straw color. The solution was allowed to reachambient temperature. The solutions were catalyzed with either a 10% (bydry mass) ammonium sulfate (AS), diammonium phosphate (DAP), ora 1:1mixture of AS and DAP. Glass composites were manufactured with thesebinders and the mechanical properties were evaluated. Dynamic MechanicalAnalysis (DMA) indicated the cure of the resin started at around 150° C.and was completed by 190° C. Results of these evaluations are describedbelow.

EXAMPLE 2

Fire resistance of the binders of Example 1 was evaluated using a flamepenetration method against other carbohydrate-based binders used inbuilding insulation. FIG. 4 shows the mass retention at 500° C. versustime of a melamine-glyoxal-dextrose compared to urea-glyoxal-dextrose.The melamine-glyoxal-dextrose was tested with two different catalysts:ammonium sulfate/ammonium phosphate and ammonium borate/ammoniumphosphate. Higher mass retention indicated higher thermal resistance.The melamine-glyoxal-dextrose binders showed superior performance.

EXAMPLE 3

The procedure of Example 1 is repeated except that after the addition ofglyoxal, the resin was kept at 80° C. to 100° C. for 60 to 120 minutes.The resulting clear dark brown resin remained clear when kept at 0° C.for 120 days. This example shows that the long-term solubility of theresin can be improved if the resin remains heated after addition ofglyoxal.

EXAMPLE 4

FIG. 5 shows the effect of the mole ratio of dextrose on the mechanicalperformance of dogbone glass composites made withmelamine:glyoxal:dextrose at mole ratios of 1:0.5:x, where x varies from6 to 12. The control was a resin based on urea:glyoxal:dextrose at1:1:5. As can be seen from these results, the level of dextrose can bevaried without a significant effect on the unaged and humid agedperformance of the resin.

EXAMPLE 5

FIG. 6 shows the effect of different catalysts at 10% by mass of thesolid resin on the performance of dogbone composites. The control was aresin based on urea:glyoxal:dextrose at 1:1:5. The best result wasobserved was observed with the 10% MC catalyst, which was a 1:1 mixtureof AS (ammonium sulfate) and DAP (diammonium phosphate). Although DMAdid not show much difference in the cure kinetics in the presence ofdifferent catalysts, MC had the best mechanical performance.

Having described several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theinvention. Additionally, a number of well-known processes and elementshave not been described in order to avoid unnecessarily obscuring thepresent invention. Additionally, details of any specific embodiment maynot always be present in variations of that embodiment or may be addedto other embodiments.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassed.The upper and lower limits of these smaller ranges may independently beincluded or excluded in the range, and each range where either, neither,or both limits are included in the smaller ranges is also encompassedwithin the invention, subject to any specifically excluded limit in thestated range. Where the stated range includes one or both of the limits,ranges excluding either or both of those included limits are alsoincluded.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise. Thus, for example, reference to “a method” includes aplurality of such methods and reference to “the curing catalyst”includes reference to one or more curing catalysts and equivalentsthereof known to those skilled in the art, and so forth. The inventionhas now been described in detail for the purposes of clarity andunderstanding. However, it will be appreciated that certain changes andmodifications may be practice within the scope of the appended claims.

What is claimed is:
 1. A fiber-reinforced composite comprising: aplurality of fibers; and a binder made from a formaldehyde-free bindercomposition comprising: melamine, a reducing sugar, a non-carbohydratealdehyde or ketone, and a curing catalyst.
 2. The fiber-reinforcedcomposite of claim 1, wherein the plurality of fibers comprises glassfibers.
 3. The fiber-reinforced composite of claim 1, wherein the binderfurther comprises a melamine salt formed by a reaction of the melaminewith the curing catalyst in the formaldehyde-free binder composition,wherein the curing catalyst is selected from a sulfate salt, a phosphatesalt, a borate salt, or combinations thereof.
 4. The fiber-reinforcedcomposite of claim 3, wherein the curing catalyst is chosen fromammonium sulfate, diammonium phosphate, ammonium borate, or combinationsthereof.
 5. The fiber-reinforced composite of claim 1, wherein theformaldehyde-free binder composition has a mole ratio of the melamine tothe reducing sugar of 1:3 to 1:12.
 6. The fiber-reinforced composite ofclaim 1, wherein the formaldehyde-free binder composition has a range ofmole ratios of melamine:non-carbohydrate aldehyde or ketone:reducingsugar of 1:0.5:6 to 1:0.5:12.
 7. The fiber-reinforced composite of claim1, wherein the reducing sugar comprises dextrose.
 8. Thefiber-reinforced composite of claim 1, wherein the non-carbohydratealdehyde or ketone is chosen from acetaldehyde, butyraldehyde,alkoxylated acetaldehyde, glutaric dialdehyde, acetone, methyl ethylketone, or pentanedione.
 9. The fiber-reinforced composite of claim 1,wherein the non-carbohydrate aldehyde or ketone comprises glyoxal. 10.The fiber-reinforced composite of claim 9, wherein a mole ratio of themelamine to the glyoxal is 2:1 to 1:3.
 11. A method of making afiber-reinforced composite, the method comprising: providing a pluralityof fibers; contacting the plurality of fibers with a formaldehyde-freebinder composition to make a fiber-binder amalgam, wherein theformaldehyde-free binder composition comprises: melamine, a reducingsugar, a non-carbohydrate aldehyde or ketone, and a curing catalyst; andheating the fiber-binder amalgam to a temperature of 100° C. to 250° C.to form the fiber-reinforced composite.
 12. The method of claim 11,wherein the plurality of fibers comprises glass fibers.
 13. The methodof claim 11, wherein the formaldehyde-free binder composition has a moleratio of the melamine to the reducing sugar of 1:3 to 1:12.
 14. Themethod of claim 11, wherein the formaldehyde-free binder composition hasa range of mole ratios of melamine:non-carbohydrate aldehyde orketone:reducing sugar of 1:0.5:6 to 1:0.5:12.
 15. The method of claim11, wherein the curing catalyst is chosen from ammonium sulfate,diammonium phosphate, ammonium borate, or combinations thereof.
 16. Themethod of claim 11, wherein the reducing sugar comprises dextrose. 17.The method of claim 11, wherein the non-carbohydrate aldehyde or ketoneis chosen from acetaldehyde, butyraldehyde, alkoxylated acetaldehyde,glutaric dialdehyde, acetone, methyl ethyl ketone, or pentanedione. 18.The method of claim 11, wherein the non-carbohydrate aldehyde or ketonecomprises glyoxal.
 19. The method of claim 18, wherein a mole ratio ofthe melamine to the glyoxal is 2:1 to 1:3.
 20. The method of claim 11,wherein the fiber-binder amalgam is heated to a temperature of 150° C.to 200° C. to form the fiber-reinforced composite.
 21. A bindercomposition comprising: melamine; a reducing sugar; and anon-carbohydrate aldehyde or ketone, wherein the binder compositionforms (i) a reaction product of only the melamine and thenon-carbohydrate aldehyde or ketone that reacts with (ii) the reducingsugar to make a crosslinked polymeric cured binder.
 22. The bindercomposition of claim 21, wherein the non-carbohydrate aldehyde or ketoneis an aldehyde comprising more than one aldehyde functional group. 23.The binder composition of claim 22, wherein the aldehyde comprising morethan one aldehyde functional group comprises a substituted glyoxalcompound.
 24. The binder composition of claim 21, wherein thenon-carbohydrate aldehyde or ketone is a carbonyl-containing compoundhaving the formula:

where R₁ and R₂ are independently selected from hydrogen, an alkylgroup, an aromatic group, an alcohol group, an aldehyde group, a ketonegroup, a carboxylic acid group, and an alkoxy group.